Security readout for executives and security teams
Plain-English summary
CVE-2021-45937 is a heap-based buffer overflow in wolfSSL wolfMQTT 1.9. It affects software that embeds that MQTT client library. The public record does not provide a CVSS score, product inventory, impact rating, or evidence of active exploitation, so urgency depends on whether the organization ships or runs wolfMQTT 1.9.
Executive priority
Do not treat this as a confirmed active-exploitation emergency from the available evidence. Prioritize inventory and patch planning where wolfMQTT 1.9 appears in shipped products or operational systems.
Technical view
The flaw is in MqttClient_DecodePacket, reached from MqttClient_WaitType and MqttClient_Connect. The references point to OSS-Fuzz reporting and an upstream wolfMQTT commit. Available sources identify wolfMQTT 1.9 but do not describe a complete affected-version range, exploitability conditions, or fixed release mapping.
Likely exposure
Exposure is most likely in embedded, IoT, or application code that statically or dynamically includes wolfSSL wolfMQTT 1.9. The bundle does not identify downstream products or CPEs.
Exploitation context
The source bundle marks CISA KEV as false and provides no cited evidence of active exploitation. Treat exploit status as unknown, not confirmed exploited.
Researcher notes
The public data is sparse: no CVSS, CWE, CPE, or detailed impact text is supplied. The most useful next step is correlating the CVE record, OSS-Fuzz entry, and upstream commit against actual wolfMQTT release history.
Mitigation direction
- Inventory applications and firmware for wolfSSL wolfMQTT 1.9.
- Check wolfSSL guidance for the corrected release or patch status.
- Review the referenced upstream commit with maintainers before backporting.
- Prioritize internet-facing or broker-connected MQTT clients first.
- Track remediation in SBOM and dependency records.
Validation and detection
- Search SBOMs, build manifests, and firmware packages for wolfMQTT.
- Confirm the wolfMQTT version compiled into each product.
- Verify whether the referenced upstream fix is present.
- Check release notes or vendor advisories for fixed-version mapping.
- Run regression testing around MQTT connect and packet handling.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2021-45937 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/wolfSSL/wolfMQTT/commit/84d4b53122e0fa0280c7872350b89d5777dabbb2CVE reference · x_refsource_MISC
- https://github.com/google/oss-fuzz-vulns/blob/main/vulns/wolfmqtt/OSV-2021-1349.yamlCVE reference · x_refsource_MISC
- https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=39083CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.